#define _CRT_SECURE_NO_WARNINGS 1
struct TreeNode* invertTree(struct TreeNode* root)
{
    if (root == NULL)
        return NULL;

    invertTree(root->left);
    invertTree(root->right);
    struct TreeNode* tmp = root->left;
    root->left = root->right;
    root->right = tmp;
    return root;
}

